Lifting jack



Nov. 20, 1928. 1,692,169 J. w. HOBBS LIFTING JACK Filed May 10, 1926 2 Sheets-Sheet l atented Nov. 26, 192

STATES PATENT OFFICE.

JOHN W. HOBBS, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO A. O.v NORTON, INC, 01' BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

Application filed May 10, 19%

position of the power devices.

A fu

LIFTING JACK.

without requiring any change therein.

er object of the invention is to provide a jack with a plurality of selective speeds operated from the same power shaft and means for shifting from one speed to the other independent of the power devices and a selected embodiment of the invention:

Fig. 1 is an elevation of the jack.

Fig.

Fig. 3 is a sectional elevation on the line is a top plan view.

3-3 Oi Fig. 1.

tom of the standard with the bevel gear 9.

A power shaft 14 is journaled iii bearings 15 in the standard and it is provided with a socket 16 adapted to receive an operating lever or bar 16. The socket may be of any kind usually employed in lifting acks to receive the operating lever or bar and suitable for this purpose, it being generally provided with a pawl and ratchet. But I do not con-- sider it necessary to enter into a detail description of this element of the jack because its particular construction does not form any part of this invention. The socket may be permanently mounted on the power shaft so far as the present invention is concerned because, as will appear herein, there is no necessity for removing the socket or changing its position on the power shaft to shift between high and low speeds.

A part 14: of the power s (Fig. 3) and a gear 17 is mounted to slide on this part and is provided with a side exten sion 17 having a groove 18. A shifter is mounted on the standard for shifting the r 17 on the power shaft between nd low speed positions, and this vertically dis v.

grooved gea haft is squared Serial No. 107,846.

19 (Fig. 4) mounted in the standard and carrying at its lower end an arm 20 which operates in the groove 18, and having a crank handle 21 on its upper end on the outside of the standard.

A sprin pressed button 22 in this handle engages the standard to hold the shifter in adjusted position.

An ic ler gear 23 (Fig. i) ournaled in the standard is in constant mesh with a high speed gear 24 keyed on the shaft 11. An idler gear 25 is journaled in the standard and is in constant mesh with the low speed gear 26 keyed on the shaft 11. The shifter gear is adapted to be shifted on the squared part of the power shaft to mesh with the high speed idler gear 23 or with the low speed idler gear 25, and this shifting of the shifter gear 17 is easily accomplished by operating the crank handle 21 and without changing the power socket or the power lever in any respect whatever. The ears 17, 23 and 24 provide a high speed chain of gearing which may be made in any desired ratio; the gears 17, 25 and 26 provide a low speed chain of gearing which may be made in any desired ratio. The gears 24 and 26 are keyed on the driven shaft 11 between the rigid bevel gear 13 and the hearing 12 of said shaft. The idler gears'23 and'25 are journaled in bearings in the standard, and by this I mean generally the shell or frame of the ark, and including thereby a skeleton frame supporting the speed mechanism en a ed with the standard and detachably in Fig. 4.

My invention is simple in construction, involves but few parts, and is capable of 013- eration easily and without the exercise of special skill.

It is highly desirable to provide a ack which is capable of lifting heavy loads as well as light loads and to facilitate the operation of the jfiClI by providing two speeds.

It is not broadly new to provide a jack with two speeds but, so far as I am aware, this has only been accomplished by providing a removable operating lever socket and shifting the socket from ge the speed. the iieessitj 1.

anoth r to ch 11 inientioi'ri H one shaftto The present as a removable socket, for shifting the socket and for providing two shafts upon which the socket may be removably mounted. Furthermore, the invention is self contained, does not require removal of parts and the speed can be easily changed by simply operating the shifter crank handle.

The desirability of providing a jack with a change of speed is largely a matter of labor and load, for with a change of speed the jack can be operated by one man to lift a light load at high speed or a heavy load at low speed, and by two men to lift a light load or a heavy load at high speed. The construction may be such that in high speed the screw will travel twice as fast as in low speed, or different ratios may be provided as desired.

Changes in the form, construction and arrangement of parts of the invention may be made without departing from the spirit or sacrificing the advantages thereof and I reserve the right to make all such changes as fall within the scope of the following claims.

I claim:

1.. A, lifting jack comprising a standard, a screw 'revolublymounted in said standard, a lifting mei'i'iber slidably mounted in said standard and adapted to be translated by by said screw, selective high speed and low speed gearing for operating said sore v, a power shaft revolubly mounted in said standarchand means slidably mounted on said power shaft for operating said gearing.

'2. A lifting jack comprising a standard, a screw revolubly mounted in said standard,

a lifting member slidably mounted in said standard and adapted to be translated by said screw, means for operating said screw comprising high speed gearing and low speed. gearing, a power shaft revolubly mounted in said standard, means slidably mounted on said power shaft and revoluble therewith forselectively operating said high speed or low speed gearing, and means projecting from the standard and cooperating with the second named means for shifting said second named means into operating po sition.

3. A lifting jack comprising a standard, a screw revolubly mounted in said standard, a lifting member slidably mounted in said standard and adapted to be translatedby said screw, means for operating said screw comprising high speed gearing and low speed gearing, a power shaft revolub'ly mounted in said standard, a gear slidably mounted on said power shaft and revoluble therewith, a shifter for selectively moving said gear into engagement with either said high or'low speed gearing, and means to revolve said power shaft.

4. A lifting jack comprising a standard, a screw revolubly mounted in said standard, a lifting member slidably .mounted in said standard and adapted to be translated by said screw, means for operatingsaid screw' comprising high speed gearing and low speed gearing, a power shaftrevolubly mounted in said standard, a gear slidably mounted on said power shaft and revoluble therewith, a grooved extension on said gear, a shifter crank on said standard, an arm engaging said groove and operated by said crank for selectively moving said gear into engagement with either said high speed or low speed gearing, and means for revolving said power shaft.

JOHN W. HOBBS. 

